Toshiba Satellite P55t-A5116 RAM Replacement

Great write-up of process, BUT VERY IMPORTANT step to insert after Step 3: With the back off, you will have access to the wide ribbon cable for the keyboard.  See the 2^nd and 3^rd photos in Step 17 below.  Before doing anything else, flip up the ribbon clamp and remove the ribbon.  Inspect the underside (electrical contact side) of the cable and blow out the connector.  Carefully fully reinstall ribbon cable, but before clamping top back down, pull cable out about the width of a hair.  Then push clamp down.  This will allow tiny pins to contact a fresh spot on the exposed runs.  Then test.  This 100% fixed multiple problems with my keyboard without doing anything else (after buying a new keyboard, now just a spare…)  and saved a TON of time and trouble.  I think some people replace the keyboard and think this is what fixed it, but doing the above would have worked.  I suspect after a few years some galvanic corrosion develops that affects the tiny connections.  This makes new connections which work perfectly.